The present invention is generally directed to toner compositions and processes thereof, and more specifically, to encapsulated toner compositions and processes thereof, and wherein in embodiments toners can be directly generated without resorting to the conventional pulverization and classification methods. In one embodiment, the present invention relates to encapsulated toner compositions which display low gloss levels of, for example, from about 0.1 gloss unit to about 25 gloss units, and more preferably from about 1 gloss unit to about 14 gloss units, as measured by the GARDNER.TM. gloss unit apparatus. In another embodiment, the present invention relates to cold pressure fixable encapsulated toners of low remanence and low gloss, such as a remanence value of from about 0.01 gauss to about 5 gauss as measured using a Half-Effect device of a Gaussmeter such as the F. W. BELL GAUSSMETER.TM. and low gloss value of from about 1 gloss unit to about 15 gloss units. In another embodiment, the present invention relates to cold pressure fixable encapsulated toners of low gloss, and low remanence and of fine particle sizes of from about 11 microns to about 21 microns in volume average diameter, and more preferably from about 13 microns to about 15 microns volume diameter, as measured by a Counter Counter. In another embodiment, the present invention relates to colored encapsulated toner compositions which display low fixing temperatures of from about 25.degree. C. to about 60.degree. C., and high fixing pressure of from about 2,000 pounds per square inch to about 4,000 pounds per square inch, thereby reducing the energy consumption of an electrostatographic imaging or printing apparatus and prolonging the lifetime of the reprographic engine. The encapsulated toners of the present invention in embodiments are comprised of a core comprised of a polymer resin and colorants, including color pigments, dyes, or mixtures thereof, and especially low remanence magnetites with, for example, diameters of from about 0.5 to about 10, and preferably 1 to 6 microns, and a light scattering components, and thereover a polymeric shell of, for example, a polyurea, a polyurethane or a polyester and the like. The processes of the present invention in embodiments thereof are comprised of an initial dispersion step for forming a stabilized organic microdroplet suspension comprised of low remanence magnetite, free-radical monomers, a deglossing agent like titanium oxide, and a shell forming monomer such as a diisocyanate suspended in an aqueous medium, followed by addition of a second monomer such as a diamine to enable formation of the polymeric shell by interfacial polymerization; and a final core resin formation step by free radical polymerization. In another embodiment, the present invention is directed to a MICR imaging process comprised of sorting security documents prepared utilizing a magnetic MICR toner comprised of resin particles and magnetite, such as MAPICO BLACK.TM., and a magnetic encapsulated toner, and wherein the images or characters developed are undetectable by known MICR devices, such as the IBM 890.TM. sorter reader or NCR 6780.TM..
In some reprographic technologies, such as xerographic or ionographic single component development systems, the fixing of toner on paper is accomplished by a high pressure fixing device utilizing minimal or no heat. More specifically, the Xerox 4068 printer and Delphax printer utilize fixing pressure of from about 2,000 pounds per square inch to about 4,000 pounds per square inch. In such systems, the conventional toner utilized is comprised of a magnetite, pigment, conductive or charge control agents, and resin, such as polyethylene wax, with a melting point of about 50.degree. to about 90.degree. C. The high pressures exerted by the rolls onto the toner on the paper substrate result in moderate fixing level, such as from about 45 percent to about 60 percent, as measured by the tape fixing method evaluated by the pull method as described in Example 1. In U.S. Pat. No. 5,043,240, a pressure fixable encapsulated toner composition is illustrated wherein a core comprised of a low glass transition temperature resin of from about -70.degree. C., and a shell comprised of a high glass transition temperature of from about 100.degree. to about 200.degree. C. is disclosed. The use of the aforementioned encapsulated toners in high pressure fixing system results in an excellent fixing level, such as from about 75 percent to about 95 percent, as measured by tape fixing method. The mechanism for excellent fixing by utilizing encapsulated toners is believed to be due to the rupture or cracking of the shell component during fixing allowing the core resin to seep out and adhere or stick onto the paper substrate. However, the use of both prior art conventional or encapsulated toner compositions results in high gloss toner images such as from about 50 gloss units to about 70 gloss units as measured by the GARDNER.TM. gloss meter. The high gloss is believed due to the high pressures exerted by the fixing device resulting in a calendered or smooth toner image. The gloss level is proportional to the smoothness of the toner image after fixing, and can easily be measured using a known GARDNER .TM. gloss unit. In some reprographic technologies, wherein black or highlight color application is desired, low gloss is desired such as less than 25 gloss units, and more preferably less than 15 gloss units as measured by the GARDNER.TM. gloss unit. Gloss values of from about 14 gloss units and below are usually known as " matte finish". However, many of the prior art encapsulated magnetic toners do not, it is believed, exhibit low gloss values, and are inferior to black and highlight color reprographic technologies which utilizes high or "cold" pressure fixing devices. The encapsulated toner compositions of the present invention alleviate the problem of high gloss and provide low gloss black and highlight colored images, and more preferably of a matte finish when transfixed using, for example, cold pressure fusers. More specifically, the encapsulated toners of this invention in embodiments utilize a magnetite of large particle size, such as from about 2 microns to about 6 microns, and a light scattering component primarily to further alleviate high gloss such as calcium carbonate, zinc stearate, titanium dioxide and the like of particle size from about 2 to about 6 microns in diameter. Accordingly, when the encapsulated toners of this invention are fixed by cold pressure devices, the toner surface is not smooth and rendered bumpy due to the large particle size of the magnetite, and light scattering of the surface results with the aid of the light scattering component, resulting in low gloss of less than about 20 gloss units and preferably less than about 15 gloss units. Furthermore, the black or colored encapsulated toners of this invention can be of a fine average particle size of from about 11 microns to about 21 microns, and more preferably from about 13 microns to about 17 microns in diameter, unattainable economically by conventional pulverization process. Additionally, the encapsulated toner compositions of the present invention in embodiments display excellent fixing characteristics, such as from about 75 percent to about 95 percent fix, as measured by the tape fixing method.
In some reprographic technologies, especially in security document processing such as checks, including for example dividend checks, turn around documents such as invoice statements like those submitted to customers by American Express and Visa, corporate checks, highway tickets, rebate checks and other documents with magnetic codes thereon, two reprographic systems are utilized. In one reprographic system, such as two component xerographic development systems or ink jet printers, a nonmagnetic toner is fixed onto paper. The aforementioned document is then subjected to a single component reprographic system, such as ionography, which fixes the magnetic toner onto paper. The resulting documents contain both a magnetic and nonmagnetic toner image and wherein only the magnetic image can be detected utilizing a MICR device such as the IBM 890.TM. or NCR 6780.TM. for sorting and security applications. However, in such process two reprographic technologies must be utilized, and as there is a need wherein the process is simplified by the use of a single reprographic system. The encapsulated toners of this invention in embodiments comprise a magnetic material, wherein the remanence is low and is of from about 0.1 to about 5 gauss, due to the large particle size and selection of magnetite which cannot be detected utilizing a MICR device such as the IBM 890.TM. or NCR 6780.TM.. Accordingly, the low remanence encapsulated toners of this invention can be imaged by single component development such as ionography, and is not magnetically read or detected by MICR devices. This allows the use of only one reprographic technology, such as a single component development ionographic system, comprised of two development housing and wherein the first development housing contains a magnetic toner which can be detected by MICR devices, and the second development house contains the encapsulated toner of this invention which cannot be detected by MICR devices. Security or sorting documents can be generated by the use of one reprographic system containing two magnetic toners of which only one magnetic toner is detected by the MICR devices. Additionally, three or more development houses in a reprographic device can be devised, wherein colored and black magnetic toners of the present invention can be utilized wherein one or more are selected as magnetically readable and one or more as magnetically nonreadable by MICR devices.
Encapsulated and MICR toners comprised of a core of a polymer and pigment like magnetite and thereover a shell are known. Disclosed in U.S. Pat. No. 4,517,268 are xerographic toners for MICR printing; U.S. Pat. No. 4,268,598 discloses a magnetic toner for the printing of machine legends; also known are magnetic encapsulated toners wherein there are selected magnetic materials, such as BAYFERROX.TM. or MAPICO BLACK.RTM. magnetites; and U.S. Pat. Nos. 3,627,682; 4,439,510; 4,536,462 and 4,581,312, the disclosures of each of the aforementioned patents being totally incorporated herein by reference. The magnetic toners of the aforementioned prior art patents comprise magnetites of a diameter in the range of from 0.2 to 0.5 micron, and of high remanence, such as from about 10 to about 20 gauss, useful for magnetically detectable images with reader sorters, such as the IBM 3890.TM. sorter reader. However, these toners are not effectively suitable for images nondetectable by sorter or reader devices. Additionally, in many instances these toners possess high gloss, as indicated herein, and a smooth developed copy finish rather than a matte or bumpy finish as is the situation with the toners of the present invention. Moreover, in U.S. Pat. No. 4,609,607 there is disclosed a magnetic toner composition and process thereof, note for example column 3, lines 64 to line 67, wherein the magnetic material has a specific area of 10 m.sup.2 /gram or less and a specific surface area of diameter of 0.1 to 2 microns. Additionally, in column 8, Example 1, through column 12, Example 12, there is disclosed a magnetite, such as EPT-1000, which has a specific surface area diameter of 0.4 micron, and the use of other magnetites of 0.2 to 1.65 microns in specific surface area diameter. Additionally, note column 12, claim 1 (a) wherein the magnetic material is of 0.1 to 2 microns in diameter. These toners do not exhibit, it is believed, low gloss when utilized in ionographic technology, such as illustrated in Comparative Example II that follows, wherein EPT-1000.RTM. magnetite (produced by Dowa Iron Powder Company)is utilized. Additionally, low remanence is not obtained, it is believed, with the use of the magnetic materials, such as EPT-1000.RTM. of the aforementioned '607 patent. Similarly, EPT-1000.RTM. magnetites are disclosed in U.S. Pat. Nos. 4,520,091; 4,576,890; 4,599,289; 4,601,968; 4,610,945; 4,642,281; 4,784,930; 4,803,144 and U.K. Patent Publications 2,137,636A and 2,135,469A. The encapsulated toners of this invention comprise large particle sizes of both magnetites and light scattering components of from about 2 microns to about 6 microns in diameter to achieve bumpy image surfaces resulting in low gloss. Additionally, low remanence is obtained with the use of larger particle size magnetites of from about 2 to about 6 microns in diameter.
In U.S. Pat. No. 4,379,825, there is disclosed a porous electrographic toner, and in column 6, Example 1, through Example 13 of column 15, magnetic materials such as iron oxides of average particle size of from 0.2 to about 2 microns are utilized. In U.S. Pat. No. 4,307,169, there is disclosed a microcapsule magnetic toner, and in column 5, Example 1, through column 11, Example 24, granular and acicular magnetites of particle size of 0.2 to 0.4 are illustrated. In U.K. Patent 1,431,699, there is disclosed a pressure fixable magnetic toner, and particularly note column 8, line 106, wherein the magnetic or magnetizable components should be finely divided, preferably submicron, and note column 8, line 112, wherein the particle sizes are of between 0.1 and 1 micron. Moreover, it is known in the art that by "fine powder" it is meant that the particles are submicron and preferably less than 1 micron. For instance, U.S. Pat. No. 4,795,698, discloses magnetic toners, and in column 12, lines 12 to 15, fine powdery magnetites are utilized of from 0.1 to 1 micron in diameter, and similarly U.S. Pat. No. 4,497,885, column 3, line 32, discloses the use of magnetites of fine powder. Moreover, U.S. Pat. No. 4,499,168, discloses magnetic encapsulated toner, and note column 7, line 1 to line 10, wherein magnetic materials of less than 2 microns are utilized. Pressure fixable encapsulated magnetic toners are disclosed in U.S. Pat. No. 4,708,924, note column 15, line 58, through column 16, line 5, wherein magnetites with average particle sizes of 0.1 to 1 micron are utilized such as in column 16, line 40, of Example 1, wherein iron oxide BL-100.RTM. produced by Titanium Kogyo Company is utilized. Other magnetic iron oxide materials such as MAPICO BLACK.RTM. produced by Columbian Chemicals, NP604.RTM. and NP604.RTM. (Northern Pigments), MO8029.RTM. and MO8060.RTM. (Mobay), CB4799.RTM., CB5300.RTM., CB5600.RTM., MCX636.RTM. (Pfizer), TMB-100.RTM. or TMB-104.RTM. (Magnox) are of fine powdery size of 0.1 to about 1 micron in diameter, such as disclosed in U.S. Pat. Nos. 5,043,240; 5,045,428; 5,080,986; 5,045,422; and European Patent 276147 A. The aforementioned prior art does not, it is believed, utilize a large particle size magnetite of about 2 to about 6 microns, light scattering components of from about 2 microns to about 6 microns in diameter, such as used in the present invention, and is necessary to achieve bumpy image surfaces resulting in low gloss. Additionally, low remanence is obtained with the use of large particle size magnetites, such as in the present invention, of from about 2 to about 6 microns in diameter, and which toners can be selected for security document applications, wherein part of the document is imaged by a low remanence toner, is not detected by MICR devices such as the IBM 890.TM. or NCR 6780.TM. reader sorters.
There is disclosed in U.S. Pat. No. 4,797,344 a magnetic toner with inorganic materials such as alumina, titanium dioxide and like, see column 4, lines 33 to 36, wherein these inorganic materials are on the toner surface and attached by blending, and note column 5, line 3 to line 15, wherein the function of the inorganic material is used to increase the mechanical strength of the toner. Moreover, in the aforementioned '344 patent, note column 4, lines 37 to 69, wherein the inorganic materials are of fine particle size and of specific surface area of 50 to 400 m.sup.2 /gram (less than 1 micron in diameter). Also, U.S. Pat. No. 4,824,754, discloses magnetic toners with metal oxides on the toner surface as flowability and electric charging purpose, and note column 5, lines 55 to 57, wherein the diameter of the metal oxide is of not larger than 1 micron, and note claim 4 wherein said particles of metallic oxide may comprise primary particles having a mean size of not more than 1 micron. Similarly, U.S. Pat. No. 4,965,162, discloses magnetic toners wherein tin oxide is utilized on the toner surface for increasing the toner's conductivity, and note column 2, lines 59 to 64, wherein the tin oxide preferably has an average size of not more than 0.3 micron.
Disclosed in U.S. Pat. No. 5,223,370 are toners with a core comprised of a polymer resin, colorants, such as pigment or dye, and thereover an inner shell comprised of a polyurea, a polyurethane, a polyether, a polyamide, or a polyester, and thereover an outer shell coating comprised of a cellulose polymer, such as methyl cellulose, a mixture of methyl cellulose and methyl ethyl cellulose, available as TYLOSE.RTM. from Fluka Biochemical Company, and the like. The aforementioned inner and outer shells are believed to yield low gloss or matte finish prints of from about one gloss unit to about 14 gloss units, especially when reprographic technologies employing VITON.RTM. fusers are utilized. However these toners are not, it is believed, magnetic and cannot be effectively utilized in reprographic technologies, such as ionography, wherein cold pressure fixing devices are employed. Additionally, in the patent there is selected an inner and outer shell to alleviate gloss. The toners of this invention utilize large particle size and low remanence magnetites as well as deglosser to alleviate gloss in cold pressure fixing devices with little or no heat.
Many of the prior art encapsulated toner compositions, particularly colored toner compositions, suffer from a number of deficiencies as indicated herein. For example, these toners do not possess, it is believed, desirable low gloss of from less than about 25 gloss units and more preferably less than 15 gloss units or a matte finish in reprography utilizing cold pressure fixing devices. Further, many of the prior art encapsulated toners do not display fusing properties such as being able to be fused at a reasonably low temperature of, for example, less than 60.degree. C. Also, many of the prior art encapsulated toners are not magnetic and cannot be utilized in reprographic single component technology, such as ionography. Also, low fixing properties, such as less than 70 percent fix level as measured by the tape fix method, are obtained with several of the prior art conventional toners. These and other disadvantages are eliminated or substantially eliminated with the processes and toner compositions of the present invention.
There is a need for toners which display low gloss values and are preferably of a matte finish, especially with black or highlight color reprographic systems employing cold pressure fixing device. Additionally, there is a need for color toners with low minimum fusing temperatures, wide fusing latitude, of fine particle size, of nonblocking tendencies, and of low remanence. These and other needs are accomplished with the encapsulated toners and processes thereof of the present invention. Specifically, with the toners of the present invention in embodiments, low gloss images of matte finish are attainable with reprographic technologies employing cold pressure fixing devices. Also, in embodiments the magnetic toners of this invention are of low remanence and cannot be detected by MICR devices. Also, the toners of the present invention possess excellent fixing properties, and do not block or agglomerate over an extended period of time, for example up to six months, in embodiments.